Wrest-pin for pianos.



J. A. MURDOCH & G. TADGELL.

WREST PIN FOR PIANOS.

APPLICATION man SEPT. 23. 1914.

1,223,41 2. Patented Apr. 24, 1917.

UNITED STATES PATENT OFFICE.

JAMES ALFRED MURDOCH, OF LONDON, AND GEORGE TADGELL, 0E 'IOTTENHAM, LONDON, ENGLAND; SAID TADGELL ASSIGNOB TO SAID MURDOCH.

wnns'r-rnv ron PIANOS.

Specification of Letters Patent.

Patented Apr. 24, 1917.

To all whom it may concern:

Be it known that we, JAMES -ALFRED MUR- DOCH, of the Allison Pianos Limited, Leighton Road, Kentish Town, N. VV., city and county of London, England, and GEORGE TADGELL, of 66 Glonmell road, Philip Lane, Tottenham, county of London, England, have invented certain new and useful Improvements in Wrest-Pins for Pianos and like Instruments, of which the following is a specification.

This invention relates more particularly to tuning pins and wrest pins in conjunction with a metallic wrest plank, although it should be distinctly understood that we do not intend to limit our invention to this single application.

I-Ieretofore considerable difficulties have been experienced with pianos as ordinarily constructed, for use in climates having extreme ranges of temperatures or having extreme conditions of humidity.

With our invention the above referred to difficulties are avoided. By providing a pin with an expanding end it becomes not only possible to make a locking fit for the pin and wire that is proof against the severest of the climatic conditions above enumerated but by means of our invention these objects are attained by means of an exceedingly simple device.

Our invention broadly speaking not only covers. the application to pianos but also to all cases where it is intended to attach a pin or stud to a plank or base.

The invention is illustrated in the accompanying drawings which show by way of example two methods of carrying the inven tion into effect.

Figure 1 is a view partly in section showing the application of a wedge for obtaining the locking of the pin and wire to the wrest plank.

Fig. 2 represents on a hollow wrest plank, another embodiment of the same invention where however a threaded screw is used instead of a wedge.

The same characters are used throughout to indicate like parts.

a represents a section of a portion of a wrest plank and b is the pin passing through a hole is, Z in the wrest plank. Said hole is preferably slightly flared at 70, though this is not absolutely essential.

The wrest plank may be formed of wood as is customary; but it may be formed with advantage of either solid or cellular metal, or hollow, the latter being preferred.

Referring to Fig. 2 the rear end 0 of the pin is bored out and tapped with a screw thread and split or cut longitudinally so that when a conical or wedge-like screw f is screwed into the tapped boring, the end of the pin becomes expanded.

The head 9 of the screw 1 may conveniently be of a shape analogous to the key end of the pin 6.

In Fig. 1, 72. represents a piano string tensioned by the pin 6, and i represents a washer which is mounted on the pin b and interposed between the string h and the wrest plank.

It will thus be seen that assuming that the wedge e is adjusted to provide the necessary expansion of the pin to resist accidental rotary movement, the rotation of the pin by the usual tuning key gradually increases the number of spires on the pin which serve as a spiral wedge to gradually draw the expanded end of the pin into the wrest plank so that accidental contrary rotation is pre vented while the string is held out of contact with the plank.

Again if for a given adjustment of the spires on the pin it becomes necessary to fasten the pin on the plank against possible rotation it is only necessary to drive in the wedge e or turn the screw head 9 so as to effectively lock the pin and wire in the wrest plank without in any way disturbing the adjustment of the tension of the wire. The pin and wedges are preferably wholly japanned, painted, plated or otherwise protected from influences of moisture. It is obvious that the above device can be employed for fastening together very effectively any two members (such as i and a) by means of a simple lmookdown structure, but many other applications will readily suggest themselves.

What we claim is.

1. In combination with a wrest plank having a hole passing therethrough, said pin passing through the hole in said wrest plank, and means for expanding one end of the pin to frictionally hold the pin in the wrest plank.

2. In combination with a wrest plank having a hole passing therethrough, a washer on one end of the said pin adjacent to the meme-1e wrest plank, said pin passing through the one end of the pin being slilbencla Wedge for hole in safl wrest plank and means for frieexpanding-file slit end to frictionally hold 10 tionally heldling the pin in the wrest plank the pin to the plank.

after the wire has been pressed. into engage- JAMES ALFRED MURDUGH. 5 menii; with the washer. GEORGE TADGELL.

3. In combination with a wrest plank hzw- Wisnesses: inga hole passing therethrough, said pin G. TURTLE,

passing threugh the hole in the wrest. plank JOHN PERCIVEL. 

